The Legacy of Mercury (Clean Virginia, Part 5)

Jun 24, 2015

A fish consumption advisory has been in effect for more than three decades on the South River and the South Fork of the Shenandoah River from Waynesboro to Front Royal.  In the next installment of WMRA’s series called “Clean Virginia,” Kara Lofton takes a look at why the advisory is still in place and what is being done to remedy the long-standing contamination.

On the banks of the South River and the South Fork of the Shenandoah River, one can see signs warning: “health advisory on eating fish…these fish may contain mercury” in both Spanish and English.

The signs are part of a monitoring program run by the Department of Environmental Quality, the Virginia Department of Health and a DuPont funded cleanup and monitoring initiative called the South River Science Team.

The pollution dates back as early as the late 1920s when a DuPont fabric factory produced Rayon. (The factory has since been sold to Invista). Mercury was used as a catalyst in the production of the fiber – a practice that was discontinued in 1950. But during those first 20 or so years, waste from the factory seeped into the soil around the plant and then into the South River, the South Fork of the Shenandoah River and part of the Shenandoah River itself.

The mercury contamination went unnoticed for 26 years until a DuPont construction team discovered mercury in the soil around the factory and notified regulation agencies of the finding.

The next year, the Virginia Department of Health issued a fish consumption ban for more than 100 miles of stream bank stretching from Waynesboro to Front Royal. The ban was amended in 1980, but a fish consumption advisory remains in effect today. Little, if any, improvements have been seen in the mercury levels found in fish tissue over the last 40 years.  

So, what’s the problem with mercury?

DON KAIN: Mercury is what they call a conservative substance, it does not degrade over time.

That was Don Kain of the Virginia Department of Environmental Quality. He said that once mercury gets into an ecosystem it stays there because it can’t be broken down like other chemicals.

KAIN: Now it can be moved, it can be transported, it can be buried and made unavailable, but if it is in the system and it’s actively working itself through the system - and that’s basically what we see with the South River and the South Fork of the Shenandoah River - it’s in the ecosystem, it’s in the invertebrates, it’s in the fish, it’s in the sediments, it’s in the floodplain soils and along the riverbanks so it basically just gets reworked and reintroduced and redeposited and restored in the river system. 

Mercury likes to stick to soil particles. When soil is washed into the rivers, mercury goes with it and is carried downstream to contaminate areas far from the actual site of pollution. The “stickiness” of mercury, makes removal of the chemical impractical if not impossible, says Michael Liberati, project director for DuPont's Corporate Remediation Group. So the South River Science Team is working on a containment, not removal, strategy.

MICHAEL LIBERATI: The South River Science Team came up with the strategy of riverbank stabilization, trying to contain the mercury rather than trying to excavate the mercury.

The plans are still being designed, but their goal is to stabilize…

LIBERATI: …the first two miles of riverbanks that are eroding and have high mercury and institute a short term and a long term monitoring program to see if that remediation is effective and if it is we are likely to continue that on down the river.

In some cases stabilization will just be vegetating the banks to keep them from eroding. In others they might use engineered fabrics to keep the riverbanks in place. Liberati says the project is still being designed, but they hope to be in the field by this time next year. If the project is successful, it would mean not only healthier fish, but an overall healthier local ecosystem for everyone.